Can I use a MacBook Pro in direct sunlight?

Yes in open shade and bright daylight, harder in direct overhead sun. That's a brightness problem and a heat problem, not just glare. On a MacBook Pro 14"/16", macOS caps the screen near half its real ceiling. MacBrightness opens the reserved range to about 1,600 nits, system-wide, so the whole screen stays readable on a sunny patio. The second limit is heat. Apple rates these for 50-95°F (10-35°C) ambient, so a glossy panel baking in full sun throttles before the brightness does. Try free Splitscreen Mode first; the full app is $5 one-time. (Air, Intel, and the M1 13" are already maxed.)